Parametric study on lattice-matched and pseudomorphic InGaAs/InAlAs/InP modulation-doped heterostructures grown by GSMBE

Modulation-doped InxGa1-xAs/InyAl1-yAs/InP heterostructures have been grown with a diffusion pumped V80H gas source molecular beam epitaxy system. Their electrical properties have been studied with Hall measurements. The effects of spacer layer thickness and buffer layer structure (InAlAs or InAlAs+InP) on lattice-matched and pseudomorphic InxGa1-xAs/InyAl1-yAs/InP 2DEGs and HEMTs characteristics have been investigated in detail. Crystalline and interface qualities can be improved by adding an InP buffer layer before the InAlAs buffer, resulting in an improvement in material electrical properties. A thicker spacer layer will cause a decrease of electron gas density and an increase of electron mobility. Adopting strained channel and Schottky layers can dramatically improve material electrical performance. For InGaAs/lnAlAs/InP pseudomorphic 2DEG (P-2DEG) structures, electron mobilities of 11230 cm(2)/V . s at n(s) of 2.3x10(12) cm(-2) at 300 K and 6.52x10(4) cm(2)/V . s at n(s) of 2.1x10(12) cm(-2) at 77 K were obtained and mu of 9273 cm(2)/V . s at 3.6x10(12) cm(-2) and 4.5x10(4) cm(2)/V . s at n(s) of 3.1x10(12) cm(-2) for both strained InGaAs channel layers and InAlAs Schottky layers in P-HEMT structures were achieved.